Abstract:

Testing the effect WAF (water accommodated fraction) on TEP (transparent exopolymers), and marine snow formation and the oil content of marine snow. Samples were collected as a time series in the Control and the WAF treatments.

Suggested Citation:

Uta Passow. 2017. Coastal water with coastal microbial concentrate (COAST): Production of TEP and CSP as a function of oil. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7PZ5759

Purpose:

This mesocosm experiment was conducted to investigate the response of a natural plankton community to dispersed oil in comparison to conditions without oil. Specifically, the effect of oil addition to a coastal community for the production of transparent exopolymer particles (TEP) and CSP (coomassie stainable particles) was tested. TEP, that are rich in polysaccharides, are central for the formation of marine snow. The role of CSP, which are protein-rich is less clear.

Data Parameters and Units:

Date (MM/DD/YYYY) Sampling Day (number) Calculations based on the whole mesocosm assume a volume of 85 liters; SSW = surrounding seawater, sample does not include marine snow; Slurry = Marine snow with some undefined fraction of SSW inadvertently included; Avg = average (of three replicate mesocosms); Stdev = standard deviation; TEP = Transparent Exopolymer Particles (mg GXeq/mesocosm); CSP = Coomassie Blue Particles (mg BSAeq/mesocosm); GXeq = Gum Xanthan equivalent; BSA eq = Bovine serum albumin equivalent; Control = Control treatment containing seawater and plankton community; WAF = Water accommodated fraction treatment, containing WAF made from the seawater (see methods) and plankton community

Methods:

In order to create an environment for controlled testing of TEP and CSP formation six 112 L capacity glass tanks (40x40x72 cm3) were used as mesocosms. Three replicate tanks were considered controls and three oil treatments, produced with a water accommodated fraction of oil (WAF; WAF-treatments). The WAF was produced using 130 liter baffled recirculating tanks (BRT) and Macondo Surrogate oil. Seawater was collected 8 kilometers off-shore south of Galveston (TX) in the Gulf of Mexico on October 17, 2015. The salinity was 31 ppt. The three Control tanks were filled directly with seawater from the storage tank (87 liters each). WAF was prepared by mixing 25 ml (5 ml ~ every 30 min for 2.5 hrs.) of Macondo Surrogate oil into 130 L of seawater then mixing for 12 to 24 hrs. The WAF was then introduced into the WAF mesocosm tanks (87 L). Plankton (≥63 µm) were collected using a net from the pier at Galveston campus. This concentrated plankton sample was introduced to the tanks and stirred (2 L to each mesocosm) immediately prior to starting the experiments. Banks of lights were placed behind each of the glass tanks and a 12:12 light dark cycle used. Samples were drawn through a 5 cm diameter Teflon faucet, positioned 10 cm from the bottom of each tank. Samples were collected every 24 hrs. up to 72 hrs. TEP concentrations were determined in triplicate using the colorimetric method and are expressed in Gum Xanthan equivalents (GXeq.) (Passow and Alldredge, 1995). Data is normalized to mesocosm volume to allow a comparison with marine snow.

Error Analysis:

Coefficient of variation (standard deviation / average) were calculated from the triplicate TEP analysis to identify problems. Averages and standard deviations were calculated from the three mesocosms of each treatment.

Provenance and Historical References:

Passow, U., Alldredge, A.L., 1995. A dye-binding assay for the spectrophotometric measurement of transparent exopolymer particles (TEP). Limnology and Oceanography 40 (7), 1326-1335.

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